<!DOCTYPE html>

<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <style>
    span{
      color: red;
    }
    div > a > span{
      color: green;
    }
  </style>
  <script defer src="xxxx/axios.js"></script>
</head>

<body>
  <div id="app">
    <a href="#">
      <span></span>
    </a>
  </div>
</body>

<script>
  document.getElementById('app').onclick = function() {
    axios.get('/index')
  }
</script>
</html>


<script>

div.style.left = '10px'
div.style.top = '10px'
div.style.width = '10px'
div.style.height = '10px'

console.log(div.offsetHeight);
console.log(div.offsetLeft);
console.log(div.offsetTop);
console.log(div.offsetWidth);









let el = document.getElementById('app')
el.style.width = (el.offsetWidth + 1) + 'px'
el.style.width = 1 + 'px'

</script>